I work in the entertainment / ticketing industry and we've been burned badly before by relying on AWS' Elastic Load Balancer due to sudden & unexpected traffic spikes.

From the article: "Elastic Load Balancer (ELB): [...] It scales without your doing anything. If it sees additional traffic it scales behind the scenes both horizontally and vertically. You don’t have to manage it. As your applications scales so is the ELB."

From Amazon's ELB documentation: "Pre-Warming the Load Balancer: [...] In certain scenarios, such as when flash traffic is expected [...] we recommend that you contact us to have your load balancer "pre-warmed". We will then configure the load balancer to have the appropriate level of capacity based on the traffic that you expect. We will need to know the start and end dates of your tests or expected flash traffic, the expected request rate per second and the total size of the typical request/response that you will be testing."

You'd be surprised about how many people don't know this. I had an expectation to scale past 1B users. I was trialling AWS when I realised through testing that it was this way. It could not deal with sudden spikes of traffic.

It's not always _users_, but requests. As companies embrace microservices, I think you'll see a moderately sized application pushing tons of requests over HTTP that would normally have used a different protocol

I don't mind. I went with dedicated hosting. I found a supplier which had their own scalable infrastructure. They already had clients which had ad server type applications that scaled into the Billions and could handle traffic spikes. With that type of setup, it was a no brainer.

I'm a sysadmin with over 10 years with Linux. So for me to setup and support servers is pretty trivial.

The agreement I had with the supplier. They managed the network and hardware 24/7. I managed the setup and support of the servers from the OS up. This arrangement worked well and I had zero downtime.

This saying holds such little value for so many engineers. They want uptime, ease of management, and security.

Most people aren't worried about squeezing another 3% performance out of thei servers. In fact I would say the slice-and-dice nature of VMs allows for better overall capacity usage because of over provisioning of resources. How many apps do you know that hover at 0.07 load all day long?

If you hadn't been a sysadmin, would still have chosen dedicated hosting? (Given that you have serious scaling requirements, of course). In other words: Would it be realistic to say that a service like Elastic Beanstalk saves on hiring a sysadmin?

Sysadmins / operations people should be able to handle anything below an OS better than your usual devops guys that would be able to build you a variation of EBS and their value further depends upon if your software has special needs that are not suitable for cloud / virtualized infrastructure.

I've heard of many start-up companies save plenty of money using dedicated hosting even without any operations / sysadmin pros around scaling to millions of users when the equivalent in AWS with relatively anemic nodes fared much better. In fact, WhatsApp only had a handful of physical servers handling billions of real users and associated internal messaging and they had developers as the on-call operations engineers.

I'm an ops engineer / developer and I'd use dedicated hosting if success depends a lot upon infrastructure costs. For example, if I started a competitor to Heroku at the same time they did, I'd definitely be having a very careful debate between dedicated / colo hosting and using a cloud provider tied intimately with my growth plans. Many companies have shockingly bad operations practices but achieve decent availability (and more importantly for most situations, profitability) just fine, so even the often-cited expectations of better networks and availability zones may be worth the risks of not caring that much.

After testing ELB and seeing the scaling issues, we ended up going to a pool of HAProxies + weighted Route53 entries. Route53 does a moderately good job of balancing between the HAProxies, and the health checks will remove an HAProxy if it goes bad. HAProxy itself is rock solid. The first bottleneck we came across was HAProxy bandwidth, so make sure the instance type you select has enough for how much bandwidth you expect to use.

Synapse is a service discovery framework. Essentially, it just writes HAProxy config files based on discovered upstreams - it does not receive any requests itself. The scalability is handled by HAProxy.

I wish Amazon would switch to a 'provisioned throughput' model for ELB like they have for DynamoDB, where you say what level of throughput you want to support and you're billed on that rather than actual traffic. Then they keep sufficient capacity available to support that service level.

So if you expect flash traffic, you just bump up your provisioned throughput. Simple and transparent.

Another gotcha is that ELB appears to load balance based on the IP addresses of the requests... We had private VPC/IP workers talking hundreds of requests per second to a non-sticky-session, public ELB fronted service (... don't ask why ...) and experienced really strange performance problems. Latency. Errors. What? Deployed a second private ELB fronting the same service and pointed the workers at it. No more latency. No more errors.

The issue appeared to have been that the private IP workers all would transit the NAT box to get to the public service and the ELB seemed to act strangely when 99.99% of the traffic was coming from one IP address. The private ELB saw requests from each of the individual IP addresses of the workers and acted a lot better. Or something.

Nginx running on a tiny instance can load balance 100k connections at thousands of requests per second. The network bandwidth for the instance will probably be saturated way before the CPU/RAM becomes a problem.

ELB (and most other managed service load balancers) are overpriced and not great at what they do. The advantage with them is easier setup and lack of maintenance.

If you're running a service with hundreds of millions or billions of requests, it's just far more effective in every way to use some small load balancing instances instead. Their Route53 service makes the DNS part easy enough with health checks.

Why do you say they're overpriced? I would say for most apps their downright cheap. Especially since you spend so little time tinkering/monitoring/worrying about them. Most people just want to work on their app not manage Nginx configs.

There is absolutely a tradeoff (as with everything in life) but in the context of this thread talking about scale with 100s of millions of requests, gigabytes of bandwidth and large spikes - it's far better to just host your own load balancers.

Most people (and apps) likely won't hit this scale so ELB is just fine. If you do though, ELB is just pricey and not really that great.